1. Field of the Invention
The present invention relates to a hand-held power tool including a housing, a drive located in the housing and including a motor, a gear unit and, optionally, a percussion mechanism. The hand-held power tool further includes ventilation means for forming a suction region and a pressure region in the housing which provide for an air flow that serves for cooling at least parts of the drive, and a separation element arranged between the suction region and the pressure region and fixedly secured in the housing.
2. Description of the Prior Art
In the hand-held power tools of the type described above, a constructive separation of the overpressure region in which ventilation means produces a blowing flow, and of the suction region in which the ventilation means produces a suction flow, insures a relatively high cooling capacity.
German Publication DE 42 20 078 A1 discloses a hand-held power tool in which a radial ventilator is located in the tool housing. The ventilator is driven by a motor and aspirates axially cooling air and presses it radially outwardly through air outlet slots from the housing. For increasing pressure and raising the volumetric flow of the radial ventilator, an air conducting element is provided therein and which is held circumferentially in the housing with a concentric cover. The cover separates the pressure region form the suction region.
In some countries, e.g., in some parts of the U.S., electrical tools and, in particular, electrically driven by an electric motor, hand-held tools must be equipped with a protective ground wire which is connected electrically with a ground conductor of the network cable for protection of metallic parts located in the interior of the housing of the electrical hand-held tool. The related metallic parts can be formed, e.g., by housing parts of the gear unit, percussion mechanism, or stator or by bare contact elements for diverting leak currents.
German Patent No. 950,658 discloses an electrical hand-held power tool the motor of which is separated from metal parts of the housing by isolating plastic parts. In addition, in the interior of the tool housing, there is provided two bare annular electrodes which are connected by a protective ground wire to ground or zero point of the network. Further, in the tool housing, there is provided a ventilator wheel that produces, during an operation, a suction region and a pressure region. The protective ground wire is freely mounted in an open transition region between the suction and pressure regions.
The drawback of the known construction consists in that because of the open transition region between the suction and pressure zones, only a relatively weak air flow is produced. In addition, the protective ground wire has a relatively high freedom of movement that can lead to damages during the operation.
Accordingly, an object of the invention is to eliminate the above-mentioned drawbacks in the electrical hand-held power tools of the type discussed above.
Another object of the present invention is to provide an electrical hand-held power tool in which a maximal cooling efficiency is possible independent from requirements in respective countries or use-specific requirement with respect to ground conductors.